Internal combustion engine



Aug. 17, 1965 P. HENSLER ETAL 4 INTERNAL COMBUSTION ENGINE Filed March 11, 1964 W n/m 5 Pau/ f/[NSZEQ flaws TOM/1L4 K ar/ PoaFF United States Patent 17 Claims. 61. 123-195 The present invention relates to an internal combustion engine, especially to an air-cooled internal combustion engine with a cylinder head made of light metal, which is Secured by means of bolts at the cylinder, possibly at the crankcase of the internal combustion engine, whereby sleeves are provided within the cylinder head for the support of the bolts.

It is already known in the prior art to support the securing bolts for a light-metal cylinder head of an internal combustion engine on sleeves inserted into the cylinder head. These prior art sleeves are thereby accommodated within bores of the cylinder head and are supported on constrictions or reductions in the cross-sectional area of the bores at a short distance from the bottom of the cylinder head. The constrictions or reduced cross-sectional areas which represent the abutment surface of the sleeves, have to be relatively Wide in order to keep the specific surface pressure of the light-metal within permissive limits. For that reason, relatively thick-walled sleeves are used. The accommodation of such sleeves and therewith the provision of bores of correspondingly large diameter within the cylinder head, however, is extremely difficult; for these bores considerably reduce the rigidity of the cylinder head. Additionally, the gas-exchange channels as Well as the spark plug and/or the injection nozzle stay in the way against an advantageous arrangement of the bores for the sleeves.

It has also been proposed therefore to support the sleeve at a threaded insert which is inserted into the cylinder head. The sleeve can be constructed thereby of smaller outer diameter, whereby the diameter of the bore in the cylinder head is also correspondingly smaller. However, the threaded insert, by reason of the surface pressure, requires also a threaded bore of large diameter. Upon heating of the cylinder head, the threaded insert lies with play within the threaded bore so that only a partial width of the thread is elfective as support. As a result thereof, there exists the danger that the threaded insert becomes loose and the clamping action of the securing bolts for the cylinder head and cylinder decreases. r

These disadvantages are eliminated by the present invention in that each of the sleeves is provided with a collar and at least the section of the sleeve having the collar is cast integral with the cylinder head of the combustion engine. As a result of these measures, bores within the cylinder head are obviated which permit an insertion of the sleeve together with the support collar of the sleeve which has a large diameter by reason of the specific surface pressure. Consequently, the securing bolts can be advantageously brought up to the cylinder seals in an optimum manner. Especially with an air-cooled cylinder head, the requisite cooling surface may be provided also with a small cylinder head. The collar is provided at one end of the sleeve and this end is cast into the cylinder head at a short distance from the bottom of the cylinder head. By such an arrangement, preferably exclusively the collar, possibly also the section of the sleeve directly adjoining the same enters into metallic combination with the material of the cylinder head during the casting. As a result thereof, a free expansion of the cylinder head during heating is made possible notwithstanding a secure anchoring of the sleeve in the cylinder head and stresses betweeen cylinder head and sleeve are avoided. Advantageously an air gap is provided between the stem of the sleeve and the cylinder head, whereby a direct heat transmission between cylinder head and sleeve is avoided. For that purpose the shank or stem of the sleeve is provided, prior to casting, with a protective layer, for example, with a layer of graphite. The sleeves serve simultaneously for the support of a bearing bridge for the valve controls of the internal combustion engine.

Accordingly, it is an object of the present invention to provide an internal combustion engine, especially an aircooled internal combusion engine, which avoids, by simple means, the aforementioned shortcomings and drawbacks encountered with the prior art constructions.

Another object of the present invention resides in the provision of an internal combution engine having a cylinder head made of light-weight metal in which the cylinder head is securely clamped to the cylinder and/or to the crankcase of the engine without requiring excessively large bores for the accommodation and/or insertion of the support sleeves.

A still further object of the present invention resides in the provision of a fastening and securing arrangement for securing the cylinder head to the cylinder of an internal combustion engine which assures reliable clamping without imparing the rigidity of the cylinder head and without involving excessively large specific surface pressures that may be harmful to any lightweight material such as aluminum, magnesium and alloys thereof from which the parts may be made.

A still further object of the present invention resides in the provision of internal combustion engines in which the support sleeves for the clamping arrangement may be readily and advantageously accommodated within bores without obstruction by the presence of the gas-exchange channels, spark plugs injection nozzles, or the like,

Another object of the present invention resides in the provision of a clamping arrangement for clamping a cylinder head to the cylinder of an internal combustion engine which permits thermal expansion of the parts Without the danger of developing undue stresses .in the materials and which also avoids the danger of possible loosening of the parts.

A still further object of the present invention resides in the provision and accommodation of supporting sleeves in internal combustion engines used for clamping the cylinder head to the cylinder block which eliminates undesirably large bores or apertures Within the cylinder head, yet assures a safe anchoring of the supporting sleeves without excessive specific surface pressures.

These and further objects, features, and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows in the single figure thereof, for purposes of illustration only, one embodiment in accordance with the present invention.

Referring now to the drawing which shows .in the single figure there of a partial cross-sectiona1 view through a cylinder head together with the cylinder and adjoining parts of the crankcase of an air-cooled internal combustion engine, reference numeral 1 generally designates therein the internal combustion engine which is provided with a crankcase 2, a cylinder 3, and a cylinder head 4. The cylinder 3 is supported on the crankcase 2 and is held together with the cylinder head 4 at the crankcase 2 by expansion bolts 5 and 6 anchored within the crankcase 2. The supports of the bolts 5 and 6 on the side of the cylinder takes place by way of sleeves 7 and 8 which are accommodated within the cylinder head 4.

The sleeves 7 and 8 are cast-in during the casting of the cylinder head 4. For that purpose, each of the sleeves 7' and 8, for example, the sleeve 7 is provided with a collar 9 which is arranged in proximity of the bottom of the cylinder head 4 and serves for the support of the axial forces acting from the expansion bolt 5 onto the sleeve 7. The collar 9 may be of any desired suitable shape and configuration whereby its size is dependent on the permissive loads, that is, on the specific surface pressure of the material of the cylinder head 4. Prior to the casting of the sleeve 7, the outer surface of the cylindrical stem 11 is provided with a protective layer or coating which prevents a combination of the material of the sleeve 7, for example, consisting of steel or a steel alloy, with the material of the cylinder head 4, for example, consisting of an alluminum alloy. Only the collar 9 of the sleeve 7, possibly also the directly adjacent area adjoining the collar 9 of the sleeve 7 is free of the protective layer so that the same combines nietallically with the cylinder head 4 during the casting operation. The collar 9 and the aforementioned parts of the sleece 7 may also be additionally pre-treated, for example, may be sand blasted or provided with a metallic intermediate layer. secure and rigid connection between the collar and the cylinder head 4. The protective layer at the stem 11 of the sleeve 7, for example, graphite, brings about that a connection between the stem 11 and the cylinder head 4 does not take place and that the cylinder head 4 can freely expand and thus any influencing of the sleeve 7 does not occur.

A gap 12 is present between the stem 11 of the sleeve 7 and the cylinder head 4. This gap 12 can be realized by a correspondingly heavy protective layer at the sleeve stem or by well known measures so that upon cooling of the cast body representing the cylinder head 4 a correspondingly large gap is formed by shrinkage. As a result thereof, direct influences on-the sleeve by heat or friction are avoided during an expansion of the cylinder head.

The sleeves 7 and 8 are constructed of such length that they extend freely beyond the cylinder head 4. A plate or bridge rests on these ends 13 and 14 which is pressed against the sleeves 7 and 8 by means of nuts 16 and 17 of the expansion bolts 5 and 6 and is thereby held securely in position. A bearing body 18 is secured at the bridge 15 by means of bolts 19 and 20. The bearing body 18 is provided with bearing pins 21 and 22 on which are mounted rocker arms 23 and 24 which serve for the control of the valves (not shown) of the internal combustion engine.

While we have shown and described one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to a person skilled in the art, and we, therefore, do not wish to be limited to these details but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

We claim:

1. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprising:

bolt means for securing said cylinder head at one of said cylinder and crankcase, sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine.

2. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprising:

A strong securing of the sleeve 7 is achieved by the bolt means for securing said cylinder at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

the collar portion being provided near one end of the sleeve means and the last-mentioned end of the sleeve means being cast into the cylinder head-at a short distance from the bottom thereof.

3. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprising:

bolt means for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means, and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

only the collar portion entering into a metallic combination with the material of the cylinder head during casting.

4. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprising:

bolt mean-s for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and with a stem portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

only the collar portion entering into a metallic combination with the material of the cylinder head during asting,

an air gap being provided between the stern portion of the sleeve means and the cylinder head.

5. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprising:

bolt means for securing said cylinder heat at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means, and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

only the collar portion and at most the section of the sleeve means directly adjoining the same entering into a metallic combination with the material of the cylinder head during casting.

6. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprisbolt means for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine, only the collar portion entering into a metallic combination with the material of the cylinder head during casting,

the stem portion being provided prior to casting with a protective layer.

7. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprising:

bolt means for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and with a stem portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

only the collar portion and at most the section of the sleeve means directly adjoining the same entering into a metallic combination with the material of the cylinder head during casting,

an air gap being provided between the stem portion of the sleeve means and the cylinder head,

the stem portion being provided prior to casting with a protective layer constituted by a coating of graphite.

8. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, compr1s1ng:

bolt means for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

the other end of the sleeve means extending beyond said cylinder head, and bearing bridge means secured to said projecting ends of the sleeve means and serving for the support of the valve control of the internal combustion engine.

9. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made or light-weight metal, a cylinder and a crankcase, comprising:

bolt means for securing said cylinder head at one of the two parts consisting of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and a stern portion, and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

the collar portion being provided near one end of the sleeve means and the last-mentioned end of the sleeve means being cast into the cylinder head at a short distance from the bottom thereof,

at most the collar portion and the section of the sleeve means directly adjoining the same entering into a metallic combination with the material of the cylinder head during casting,

an air gap being provided between the stem portion of the sleeve means and the cylinder head,

said stern portion being provided prior to casting with a protective layer constituted by a coating of graphite,

the other end of the sleeve means extending beyond said cylinder head, and bearing bridge means secured to said projecting ends of the sleeve means and serving for the support of the valve control of the internal combustion engine.

10. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprismg:

5 bolt means for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine, the collar portion being provided near one end of the sleeve means and the last-mentioned end of the sleeve means being cast into the cylinder head at a short distance from the bottom thereof, only the collar portion entering into a metallic combination with the material of the cylinder head during casting,

the stem portion being provided prior to casting with a protective layer.

11. In an internal combustion engine, especially in an air-cooled internal combustion engine of the type which includes a cylinder head made of light-weight met-a1, a cylinder and a crankcase, and in which the cylinder head is clamped to one of the two parts consisting of the cylinder and crankcase by means of expansion bolts resting on abutment sleeves provided in the cylinder head,

the improvement essentially consisting of each of said sleeves being provided With a collar portion and the section of the sleeve containing the collar portion being cast integral with the cylinder head of the internal combustion engine.

12. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprismg:

bolt means for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine, the collar portion being provided near one end of the sleeve means and the last-mentioned end of the sleeve means being cast into the cylinder head at a short distance from the bottom thereof,

only the collar portion entering into a metallic combination with the material of the cylinder head during casting.

13. In an internal combustion engine, especially in an air-cooled internal combustion engine of the type which includes a cylinder head made of light-weight metal, a cylinder and a crankcase, and in which the cylinder head is clamped to one of the two parts consisting of the cylinder and crankcase by means of expansion bolts resting on abutment sleeves provided in the cylinder head,

the improvement essentially consisting of each of said sleeves being provided with a collar portion and the section of the sleeve containing the collar portion being cast integral with the cylinder head of the internal combustion engine,

the collar portion being provided near one end of the sleeve and being cast integral with the cylinder head at a short distance from the bottom thereof.

14. An internal combustion engine, especially an aircooled internal combustion engine having a cylinder head made of light metal, a cylinder and a crankcase, comprismg:

bolt means for securing said cylinder head at one of said cylinder and crankcase,

sleeve means within said cylinder head for the support of said bolt means,

and each of said sleeve means being provided with a collar portion and with a stem portion and at least the section containing the collar portion of the sleeve means being cast into the cylinder head of the internal combustion engine,

the collar portion being provided near one end of the sleeve means and the last-mentioned end of the sleeve means being cast into the cylinder head at a short distance from the bottom thereof,

only the collar portion entering into a metallic combination with the material of the cylinder head during casting,

an air gap being provided between the stem portion of the sleeve means and the cylinder head.

15. In an internal combustion engine, especially in an air-cooled internal combustion engine of the type which includes a cylinder head made of light-weight metal, a cylinder and a crankcase, and in which the. cylinder head is clamped to one of the two parts consisting of the cylinder and crankcase by means of expansion bolts resting on abutment sleeves provided in the cylinder head,

the improvement essentially consisting of each of said sleeves being provided with a collar portion and the section of the sleeve containing the collar portion being cast integral with the cylinder head of the 7 internal combustion engine,

an air gap being provided between the stem portion of a respective sleeve and the cylinder head.

16. In an internal combustion engine, especially in an air-cooled internal combustion engine of the type which includes a cylinder head made of light-Weight metal, a cylinder and a crankcase, and in which the cylinder head is clamped to one of the two parts consisting of the 8 cylinder and crankcase by means of expansion bolts resting on abutment sleeves provided in the cylinder head,

the improvement essentially consisting of each of said "sleeves being provided with a collar portion and the section of the sleeve containing the collar portion being cast integral with the cylinder head of the internal combustion engine, and the other end of a sleeve extending beyond said cylinder head, and bearing bridge means secured to the projecting ends of the sleeves and serving for the support of the valve control of the intern-a1 combustion engine. I 17. In an internal combustion engine, especially in an air-cooled internal combustion engine of the type which includes a cylinder head made of light-weight metal, a cylinder and a crankcase, and in which the cylinder head is clamped to one of the two parts consisting of the cylinder and crankcase by means of expansion bolts resting on abutment sleeves provided in the cylinder head,

the improvement essentially consisting of each of said sleeves being provided with a collar portion and the section of the sleeve containing the collar portion being cast integral with the cylinder head of the internal combustion engine,

the collar portion being provided near one end of the sleeve and being cast integral with the cylinder head at a short distance from the bottom thereof, an air gap being provided between the stem portion of a respective sleeve and the cylinder head.

References Cited by the Examiner UNITED STATES PATENTS 3,046,953 7/62 Dolza l23l95 r KARL J. ALBRECHT, Primary Examiner. 

1. AN INTERNAL COMBUSTION ENGINE, ESPECIALLY AN AIRCOOLED INTERNAL COMBUSTION ENGINE HAVING A CYLINDER HEAD MADE OF LIGHT METAL, A CYLINDER AND A CRANKCASE, COMPRISING: BOLT MEANS FOR SECURING SAID CYLINDER HEAT AT ONE OF SAID CYLINDER AND CRANKCASE, SLEEVE MEANS WITHIN SAID CYLINDER HEAD FOR THE SUPPORT OF SAID BOLT MEANS, AND EACH OF SAID SLEEVE MEANS BEING PROVIDED WITH A COLLAR PORTION AND AT LEAST THE SECTION CONTAINING THE COLLAR PORTION OF THE SLEEVE MEANS BEING CAST INTO THE CYLINDER HEAD OF THE INTERNAL COMBUSTION ENGINE. 